Develop Reference

Activity with launchMode singleTop or singleTask is always recreated

The MainActivity in my app has a launchMode of singleTop defined in the manifest file. Whenever I click a notification my MainActivity is re-created and the old instance is destroyed. MainActivity is visible and in the foreground when the notification is clicked, so I would assume the intent would be passed to the current instance's onNewIntent(), but this never happens. Here is the intent I create:
Intent resultIntent = new Intent(App.getInstance(), MainActivity.class);
TaskStackBuilder stackBuilder = TaskStackBuilder.create(App.getInstance());
stackBuilder.addNextIntent(resultIntent);
PendingIntent resultPendingIntent = PendingIntent.getActivity(App.getInstance(), 0, resultIntent, PendingIntent.FLAG_UPDATE_CURRENT);
I sometimes add the FLAG_ACTIVITY_CLEAR_TOP and FLAG_ACTIVITY_SINGLE_TOP to the intent like so:
resultIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP);
I have also tried using the singleTask launchMode also with those flags and the same behavior has happened. Could someone lend some insight on this behavior?

You don't need to create a new TaskStackBuilder. Try intent which acts like you want to restart the application, but singleTop will keep it from doing so:
Intent resultIntent = new Intent(App.getInstance(), MainActivity.class);
resultIntent.setAction(Intent.ACTION_MAIN);
resultIntent.addCategory(Intent.CATEGORY_LAUNCHER);
PendingIntent resultPendingIntent = PendingIntent.getActivity(App.getInstance(), 0, resultIntent, PendingIntent.FLAG_UPDATE_CURRENT);

Android start the same activity but close previous one

I am trying to start my activity from the notification and it is working but instead of starting the same activity, another (copy) of my activity gets launched when i exit from it I find another copy of the activity beneath it.
NotificationCompat.Builder b = new NotificationCompat.Builder(this);
....
Intent intent = new Intent(this, MyActivity.class);
intent.putExtra("item", currentObj);
PendingIntent pIntent = PendingIntent.getActivity(this, 0, intent, 0);
....
b.setContentIntent(pIntent);
how can I fix this ??

you have to use TaskStackBuilder and add its parent
TaskStackBuilder stackBuilder = TaskStackBuilder.create(context);
// Adds the back stack for the Intent (but not the Intent itself)
stackBuilder.addParentStack(MainActivity.class);
stackBuilder.addNextIntent(resultIntent);
and you have add it in the notification
stackBuilder.addParentStack(MainActivity.class);
What it does is simple it just says android about the parent of the present class you have opened! This should slove your problem. I hope this is helpful. Thankyou

You can call finish(); before b.setContentIntent(pIntent);.

There is a flag you can set that starts the same activity instead of a new one each time:
Intent intent = new Intent(this, MyActivity.class);
intent.putExtra("item", currentObj);
intent.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);

You can add this line to your Activity inside manifest to prevent from loading the same activity multiple times
android:launchMode = "singleInstance"
OR
Flag the intent before starting Activity like this
intent.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);

Android Notification back stack

The MainActivity calls ActivityA, and then it receives a notification for ActivityA, now the back stack is [MainActivity, ActivityA], if click the notification, the current back stack should not change; If not click the notification, and back to MainActivity and then into ActivityB, the back stack is now [MainActivity, ActivityB], if click the notification now, the expected back stack is [MainActivity, ActivityB, ActivityA], but I get [MainActivity, ActivityA] instead. My code is below:
Intent backIntent = new Intent(this, MainActivity.class);
Intent intent = new Intent(this, NotificationActivity.class);
PendingIntent pendingIntent = PendingIntent.getActivities(this, 0,
new Intent[] {backIntent, intent}, PendingIntent.FLAG_UPDATE_CURRENT);
I find a similar problem in Back to main activity from notification-created activity, but it seems not suit for me.

Launching an activity of the application on clicking the notification

I like to launch one of my activities in my application on clicking the notification.
I designed a pending intent as discussed in the link Notifications.
But when i click the notification, an activity is launched but that is not the activity supposed to launch from my application. Just the activity that has same class name as my activity is launched. I set a break point in my activity and the break point is never hit.
What is wrong? NotificationListActivity is the one I like to launch. Now the activity titled with NotificationListActivity is launched, but not my activity.
Intent resultIntent = new Intent(thisclasscontext, NotificationListActivity.class);
resultIntent.putExtra("MOBILENUMBER", tel);
TaskStackBuilder stackBuilder = TaskStackBuilder.create(thisclasscontext);
// Adds the back stack for the Intent (but not the Intent itself)
stackBuilder.addParentStack(NotificationListActivity.class);
// Adds the Intent that starts the Activity to the top of the stack
stackBuilder.addNextIntent(resultIntent);
PendingIntent resultPendingIntent = stackBuilder.getPendingIntent(0, PendingIntent.FLAG_UPDATE_CURRENT);
mBuilder.setContentIntent(resultPendingIntent);

You can use the below as a reference it works
public void notification()
{
int mId=1;
NotificationCompat.Builder mBuilder =
new NotificationCompat.Builder(this)
.setSmallIcon(R.drawable.ic_launcher)
.setContentTitle("My notification")
.setContentText("Hello World!");
// Creates an explicit intent for an Activity in your app
Intent resultIntent = new Intent(MainActivity.this, SecondActivity.class);
// The stack builder object will contain an artificial back stack for the
// started Activity.
// This ensures that navigating backward from the Activity leads out of
// your application to the Home screen.
TaskStackBuilder stackBuilder = TaskStackBuilder.create(MainActivity.this);
// Adds the back stack for the Intent (but not the Intent itself)
stackBuilder.addParentStack(SecondActivity.class);
// Adds the Intent that starts the Activity to the top of the stack
stackBuilder.addNextIntent(resultIntent);
PendingIntent resultPendingIntent =
stackBuilder.getPendingIntent(
0,
PendingIntent.FLAG_UPDATE_CURRENT
);
mBuilder.setContentIntent(resultPendingIntent);
NotificationManager mNotificationManager =
(NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
// mId allows you to update the notification later on.
mNotificationManager.notify(mId, mBuilder.build());
}

How to launch activity from click on notification?

How do I launch an activity when the user clicks on the notification? I am having constant crashes. I can not get the click on the notification to work. There is an onclick method shown below. When a button called ButtonOne is pressed, it will launch a notification in the top menu bar of the screen. I wanted to user to be able to press the notification and have it launch the activity called MainActivity. It crashes and will not launch the page. There is probably something wrong in my code for notification that I put inside of the MainActivity class. What is wrong?
ButtonOne.setOnClickListener(new View.OnClickListener() {
private int mId;
// anonymous inner class override for on click
public void onClick(View v) {
Intent myIntent = new Intent(MainActivity.this, CoverFlowExample.class);
MainActivity.this.startActivity(myIntent);
NotificationCompat.Builder mBuilder =
new NotificationCompat.Builder(MainActivity.this)
.setSmallIcon(R.drawable.ic_launcher)
.setContentTitle("My notification")
.setContentText("Hello World!");
// Creates an explicit intent for an Activity in your app
Intent resultIntent = new Intent(MainActivity.this, MainActivity.class);
// The stack builder object will contain an artificial back stack for the
// started Activity.
// This ensures that navigating backward from the Activity leads out of
// your application to the Home screen.
TaskStackBuilder stackBuilder = TaskStackBuilder.create(MainActivity.this);
// Adds the back stack for the Intent (but not the Intent itself)
stackBuilder.addParentStack(MainActivity.class);
// Adds the Intent that starts the Activity to the top of the stack
stackBuilder.addNextIntent(resultIntent);
PendingIntent resultPendingIntent =
stackBuilder.getPendingIntent(
0,
PendingIntent.FLAG_UPDATE_CURRENT
);
mBuilder.setContentIntent(resultPendingIntent);
NotificationManager mNotificationManager =
(NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
// mId allows you to update the notification later on.
mNotificationManager.notify(mId, mBuilder.build());
}
});

Found out that the problem was the AVD android emulator not the code. For some reason it did not update the code from earlier version. Tested it again and now it runs with no errors.